Corrosion resistance of electrodeposited RE-Ni-W-P-SiC composite coating

1　ＩＮＴＲＯＤＵＣＴＩＯＮＭａｋｉｎｇｕｓｅｏｆｃｏｍｐｏｓｉｔｅｍａｔｅｒｉａｌｓｉｓｔｈｅｄｅｖｅｌ ｏｐｉｎｇｔｒｅｎｄｉｎｔｈｅｃｕｒｒｅｎｔｍａｔｅｒｉａｌｓｓｃｉｅｎｃｅ .Ｉｔｍｅａｎｓｏｂｔａｉｎｉｎｇａｎｅｗｃｏｍｐｏｓｉｔｅｍａｔｅｒｉａｌｂｙｃｏｍｂｉｎｉｎｇｔｈｅｂｅｓｔｐｒｏｐｅｒｔｉｅｓｏｆｓｅｖｅｒａｌｄｉｆｆｅｒｅｎｔｍａｔｅｒｉａｌｓｓｏａｓｔｏｍｅｅｔｐｅｏｐｌｅ’ｓｄｅｍａｎｄｓ .Ｃｏｍｐｏｓｉｔｅｅｌｅｃｔｒｏｐｌａｔｉｎｇｉｓｏｎｅｏｆｔｈｅｍｏｓｔｕｓｅ…     

电沉积RE-Ni-W-P-SiC-PTFE非晶态复合材料的组织及结构

在碳钢表面进行了RE-Ni-W-P-SiC-PTFE(聚四氟乙烯)非晶态复合材料镀层的电沉积试验，研究了镀液的pH值、电流密度和热处理温度等因素对镀层的组织和相结构的影响，确定了电沉积工艺的最佳条件。结果表明，镀态镀层以非晶态的形态存在，随着热处理温度的升高，镀层逐渐向晶态转变，Ni3P相的衍射峰逐渐加强；在低于400℃时，镀层中含有PTFE相，在400％以上时，PTFE相已不存在，同时镀层中出现了W3O、NiO及(FeNi)相；500％时镀层已完全晶化，此时的物相组成与400％相近，只是W3O相被WO2代替。     

Microstructure of electrodeposited RE-Ni-W-P-SiC composite coating

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｃｏｍｐｏｓｉｔｅｅｌｅｃｔｒｏｐｌａｔｉｎｇｔｅｃｈｎｉｑｕｅａｓａｎｅｗｆｕｎｃｔｉｏｎａｌｐｌａｔｉｎｇｍｅｔｈｏｄｉｓａｔｔｒａｃｔｉｎｇｐｅｏｐｌｅ’ｓａｔｔｅｎ ｔｉｏｎｓ,ｅｓｐｅｃｉａｌｌｙｔｈｅｒｅｈａｓｂｅｅｎａｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔｉｎｔｈｅｒｅｃｅｎｔｔｅｎｓｏｆｙｅａｒｓ.Ｆｕｒｔｈｅｒｍｏｒｅ,ｍｏｓｔｃｏｍ ｐｏｓｉｔｅｔｅｃｈｎｉｑｕｅｓｈａｖｅｂｅｅｎｕｓｅｄｉｎｉｎｄｕｓｔｒｉｅｓ[1～ 6 ].Ｒａｒｅｅａｒｔｈ(ＲＥ)ｅｌｅｍ…     

Effects of pulse current on properties of electrodeposited RE-Ni-W-P-SiC composite coating

Effects of pulse current on properties of electrodeposited RE-Ni-W-P-SiC composite coating were studied. The results show that hardness of the pulse current electrodeposited composite coatings is higher than that of the direct current electrodeposited composite coatings while other parameters are the same. Otherwise, the deposited velocity is higher, and wear resistance and corrosion resistance of the pulse current electrodeposited composite coatings are also improved when the average current density is 10 A/dm2 , pulse frequency is 800 Hz and duty ratio is 1: 5. The hardness of the coating as-deposited is HV500 - 700, and it reaches HV1300 after heat treatment at 400 ℃ for 1 h.     

Corrosion behavior of Zn-Ni-Al2O3 composite coating

The corrosion behavior and anti-corrosion mechanism of the Zn-Ni-Al2O3 composite coating were investigated by SEM, EDS and XPS.The results indicate that the corrosion type of the Zn-Ni-Al2O3 coatings in neutral 5 wt.% NaCl solution is uniform corrosion.The presence of compact and uniformly dispersed nano alumina particles substantially inhibits the corrosion of Zn-Ni-Al2O3 composite coatings.In the initial corrosion stage, the corrosive products of Zn-Ni matrix form a compact ZnCl2·4Zn(OH)2 layer.With the development of corrosion, some nano alumina particles are embedded and form a Ni enrichment layer.In Ni enrichment layer, Ni presents as Ni and NiO.     

Characteristics of electrodeposited RE-Ni-W-B-B_4C-MoS_2 composite coating

1　INTRODUCTIONByuseofthecompositeelectrodepositingtech nique ,codepositionofsolidhardparticleswithmetalmatrixonthesurfacetoformacompositecoatingisoneoftheeffectivemethodstoimprovetheabrasionresistanceofmaterialsurface[16 ] .Furthermore ,thecompositeelectrodepositingtechniquehasmanyad vantages ,suchassimpleprocess ,lowcost,operationatambienttemperatureanduninfluenceontheprop ertiesoftheinsidematrixmaterial,soitholdsanim portantstatusintheresearchanddevelopmentofabrasion resistantandantifri…     

碳纳米管/镍基复合镀层的腐蚀行为

采用复合沉积方法在普通碳钢基底上沉积碳纳米管／镍基复合镀层。用腐蚀实验、电化学方法研究了复合镀层在3．5％NaCl溶液中的耐腐蚀性能，并讨论了其耐腐蚀机理，对普通碳钢和纯镍镀层也进行了比较研究。结果表明：碳纳米管的加入显著提高了复合镀层的耐腐蚀性能；耐腐蚀的原因在于碳纳米管的复合镀层更加致密，隔离了腐蚀介质，并阻止了蚀坑的增大，同时，碳纳米管促进了镍的纯化，从而提高镀层的耐蚀性。     

镍磷非晶纳米晶复合镀层的制备及其耐蚀性

对电沉积12．3％P（质量分数）镍磷合金进行热处理，部分晶化获得非晶纳米晶复合镀层。利用X射线衍射仪、透射电镜和高分辨透射电镜分析镀层的结构。结果表明，镀态时镀层呈典型的非晶态结构，控制热处理工艺可得到非晶纳米晶的复合镀层。通过动电位极化曲线（3．5％NaCI溶液）测定，得知部分晶化的镀层耐蚀性得到改善。由于具有少量纳米晶相镶嵌于连续非晶相上，非晶纳米晶复合结构的镍磷合金镀层耐蚀性优于非晶态镍磷合金镀层。     

Sliding wear behaviors of electrodeposited Ni composite coatings containing micrometer and nanometer Cr particles

Micrometer and nanometer Cr particles were co-deposited with Ni by electroplating from a nickel sulfate bath containing a certain content of Cr particles. Cr microparticles are in a size range of 1-5 (m and Cr nanoparticles have an average size of 40 nm. The friction and the wear performance of the co-deposited Ni-Cr composite coatings were comparatively evaluated by sliding against Si3N4 ceramic balls under non-lubricated conditions. It is found that the incorporation of Cr particles enhances the microhardness and wear resistance of Ni coatings. The wear resistance of Ni composite coating containing Cr nanoparticles is higher than that of the Ni composite coating containing Cr microparticles with a comparable Cr particle content. The co-deposition of smaller nanometer Cr particles with Ni effectively reduces the size of Ni crystals and significantly increases the hardness of the composite coatings due to grain-refinement strengthening and dispersion-strengthening, resulting in a significant improvement of wear resistance of the Ni-Cr nanocomposite coatings.     

Corrosion resistance of thermal sprayed titanium coatings in chloride solution

The corrosion behavior of a resin-sealed flame-sprayed titanium coating in 3.5% NaCl solution was investigated by electrochemical polarization measurements. The composition and structure of the sprayed film was also analyzed by scanning electron microscopy (SEM) and electron probe x-ray microanalysis (EPMA). Although an as-sprayed titanium coating exhibited no resistance to corrosion because of its porosity, the sprayed titanium sealed with epoxy or silicon resin showed an excellent resistivity with respect to chloride corrosion. Although almost half of the titanium changed to oxides, nitrides, and carbides through the wire flame spraying, the conversion of the metal to those compounds had little effect on decreasing the corrosion resistivity. The sprayed and sealed titanium coating obtained by conventional on-site thermal spraying is expected to be an economical material for chloride containing environments. Presented at United Thermal Spray Conference & Exposition ’97, 15–18 September 1997, Indianapolis, IN.     

SiC颗粒尺寸对镍基复合镀层耐磨性和耐蚀性的影响

在正交实验基础上,对比研究微米SiC(平均粒径1.5 μm)和纳米SiC(平均粒径20 nm)增强复合镍基镀层的摩擦磨损行为和耐腐蚀性能.通过TEM、SEM、EDX和XRD等手段研究颗粒分散状态以及复合镀层的表面和截面形貌、成分及相结构.采用球-盘滑动摩擦磨损试验机研究复合镀层的耐磨性.电化学阻抗谱测量在3.5%的NaCl水溶液中进行.结果表明:微米级颗粒增强复合镀层可以获得更高的表面硬度,两种增强复合镀层具有相似的摩擦磨损行为.电化学阻抗谱分析表明:SiC颗粒的加入可以提高镀层的耐腐蚀性,且纳米颗粒复合镀层具有更好的耐蚀性.     

Properties and structure of RE-Ni-W-P-SiC composite coating prepared by impulse electrodeposition

The properties and structure of electrodeposited RE （CeO2）-Ni-W-P-SiC composite coating were investigated. The results show that the hardness and electrodepositing speed of composite coatings obtained at an impulse current are higher than those at a direct current. The hardness and wear resistance of the coating are obviously increased by adding RE and SiC. The hardness of the coating increases with the increase of treatment temperature and current density, and reaches the optimum value at 400 ℃ and at 10 A/dm^2, respectively. The optimum operation parameters of electrodeposition of the composite coating are as follows： pH value is 4.5, bath temperature is 65 ℃, and current density is 10 A/dm^2.     

Oxidation resistance of co-deposited Ni-SiC nanocomposite coating

Ni-6.0%SiC （mass fraction） nanocomposite coating was prepared from a nickel sulfate bath by co-electrodeposition of Ni and SiC nanoparticles in an average size of 30 nm. The oxidation at 1 000 ℃ shows that the Ni-6.0%SiC nanocomposite coating has a superior oxidation resistance compared with the pure Ni film due to the formation of SiO2 oxide particles along grain boundaries, blocking the outward diffusion of Ni and changing the oxidation growth mechanism. The effect of SiC nanoparticles on the oxidation progress was discussed in detail.     

纯铜热化学反应热喷涂陶瓷/渗铝复合涂层耐蚀性研究

采用火焰喷涂技术在铜基体表面先后喷涂渗铝层和陶瓷涂层,并加热保温,制备成铜基陶瓷/渗铝复合涂层。用XRD和SEM对涂层进行组织结构分析和形貌观察,并测试涂层的硬度、抗热震性和耐蚀性。结果表明,复合涂层中有Cu9Al4、Cu5Zn8、Cu3Ti等新相生成;渗铝层部分有γ2相（Cu9Al4）析出且涂层与基体结合紧密;复合涂层的硬度为82～87 HRE,其耐热震次数可达50次以上;复合涂层封孔后的耐酸蚀能力提高到基体的16倍,耐盐蚀能力提高到基体的25倍;极化试验表明,复合涂层抗电化学腐蚀能力显著增强,其耐蚀性能远优于纯铜渗铝层和单纯陶瓷涂层。     

Reactive HVOF sprayed TiN-matrix composite coating and its corrosion and wear resistance properties

TiN-matrix composite coating was prepared on 45# steel by reactive high-velocity oxy-fuel (HVOF) spraying. Its microstructure, phase composition, micro-hardness, corrosion resistance in 3.5% NaCl solution and wear resistance were analyzed. The results suggest that the TiN-matrix composite coating is well bonded with the substrate. The micro-hardness measured decreases with the increase of applied test loads. And the micro-hardness of the coating under heavy loads is relatively high. The TiN-matrix composite coating exhibits an excellent corrosion resistance in 3.5% NaCl solution. The corrosion potential of coating is positive and the passivation zone is broad, which indicates that the TiN-matrix composite coating is stable in the electrolyte and provides excellent protection to the substrate. The wear coefficient of the coating under all loads maintains at 0.49–0.50. The wear mechanism of the coating is revealed to be three-body abrasive wear. Yet the failure forms of TiN-matrix composite coating under different loads have an obvious difference. The failure form of coating under light loads is particle spallation due to the stress concentration while that of coating under heavy loads is cracking between inter-lamellae.     

Theoretical study of hardness variation with pulse parameters in composite coatings electrodeposited by pulsed currents

Theoretical aspects of the electrodeposition of composite coatings prepared by pulsed currents and also the variation of coatings hardness with the pulse parameters have been presented in this paper. The effect of the grain size, polarisation, pulse-plating parameters and incorporation of ceramic particles on the hardness or flow stress are also reported. The theoretical relationship obtained showed that with increasing polarisation and particle incorporation, the hardness of the coatings was increased. In addition, by decreasing the grain size, frequency and duty cycle the hardness was increased.     

Corrosion behavior of sintered zinc-aluminum coating in NaCl solution

Sintered zinc-aluminum coating (SZAC) was prepared using zinc flakes,aluminum flakes and CrO3 as main raw materials,The corrosion behavior of SZAC in 3.5NaCl solution was Studied by means of SEM,EDS,EIS and so on.Results indicate that aluminum corroded in advance of zinc to produce speculate or spherical substances,which attaches to SZAC and adds mass to it.Corrosion production passivates metal powders in SZAC.causes Ecorr of SZAC to increase gradually,and causes the arising of the third time constant in EIS,which corresponds to the insulation of corrosion production.     

坡莫合金在中性氯离子溶液中的腐蚀行为

针对金属薄膜复合板的金属膜选材问题,采用电子探针、金相显微镜研究了坡莫合金膜的成分、显微组织,利用电化学技术,辅以浸泡法研究了坡莫合金在浓度为2.4 mol/L的中性氯化钠溶液中的电化学腐蚀行为,利用SEM和EDS研究了腐蚀产物和腐蚀形貌,结果表明:坡莫合金膜晶粒度8级,组织为奥氏体,腐蚀类型为局部腐蚀,主要表现为晶间...